US Patent 8115683 Rectenna solar energy harvester

A rectenna is a combination of an antenna and a rectifier (diode). Because of limitations in nanotechnology fabrication, it has not been possible to develop rectennas that can operate in the visible frequency range. Current work has gone to producing rectennas that operate in the far infrared (thermal emission) frequency range. To harvest solar energy with rectennas to produce electric power and since rectennas cannot operate at such high frequencies, the present invention provides rectenna configurations to overcome this problem.